Newly expressed SUR1-regulated NC(Ca-ATP) channel mediates cerebral edema after ischemic stroke

Glibenclamide Directly Prevents Neuroinflammation by Targeting SUR1-TRPM4-Mediated NLRP3 Inflammasome Activation In Microglia

Glibenclamide (GLB) reduces brain edema and improves neurological outcome in animal experiments and preliminary clinical studies. Recent studies also suggested a strong anti-inflammatory effect of GLB, via inhibiting nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3) inflammasome activation. However, it remains unknown whether the anti-inflammatory effect of GLB is independent of its role in preventing brain edema, and how GLB inhibits the NLRP3 inflammasome is not fully understood. Sprague-Dawley male rats underwent 10-min asphyxial cardiac arrest and cardiopulmonary resuscitation or sham-operation. The Trpm4 siRNA and GLB were injected to block sulfonylurea receptor 1-transient receptor potential M4 (SUR1-TRPM4) channel in rats. Western blotting, quantitative real-time polymerase chain reaction, behavioral analysis, and histological examination were used to evaluate the role of GLB in preventing NLRP3-mediated neuroinflammation through inhibiting SUR1-TRPM4, and corresponding neuroprotective effect. To further explore the underlying mechanism, BV2 cells were subjected to lipopolysaccharides, or oxygen-glucose deprivation/reperfusion. Here, in rat model of cardiac arrest with brain edema combined with neuroinflammation, GLB significantly alleviated neurocognitive deficit and neuropathological damage, via the inhibition of microglial NLRP3 inflammasome activation by blocking SUR1-TRPM4. Of note, the above effects of GLB could be achieved by knockdown of Trpm4. In vitro under circumstance of eliminating distractions from brain edema, SUR1-TRPM4 and NLRP3 inflammasome were also activated in BV2 cells subjected to lipopolysaccharides, or oxygen-glucose deprivation/reperfusion, which could be blocked by GLB or 9-phenanthrol, a TRPM4 inhibitor. Importantly, activation of SUR1-TRPM4 in BV2 cells required the P2X7 receptor-mediated Ca2+ influx, which in turn magnified the K+ efflux via the Na+ influx-driven opening of K+ channels, leading to the NLRP3 inflammasome activation. These findings suggest that GLB has a direct anti-inflammatory neuroprotective effect independent of its role in preventing brain edema, through inhibition of SUR1-TRPM4 which amplifies K+ efflux and promotes NLRP3 inflammasome activation.

Neuroprotective effects of Lasmiditan and Sumatriptan in an experimental model of post-stroke seizure in mice: Higher effects with concurrent opioid receptors or KATP channels inhibitors

BACKGROUND

Early post-stroke seizure frequently occurs in stroke survivors within the first few days and is associated with poor functional outcomes. Therefore, efficient treatments of such complications with less adverse effects are pivotal. In this study, we investigated the possible beneficial effects of lasmiditan and sumatriptan against post-stroke seizures in mice and explored underlying mechanisms in their effects.

METHODS

Stroke was induced by double ligation of the right common carotid artery in mice. Immediately after the ligation, lasmiditan (0.1 mg/kg, intraperitoneally [i.p.]) or sumatriptan (0.03 mg/kg, i.p.) were administered. Twenty-four hours after the stroke induction, seizure susceptibility was evaluated using the pentylenetetrazole (PTZ)-induced clonic seizure model. In separate experiments, naltrexone (a non-specific opioid receptor antagonist) and glibenclamide (a K_ATP channel blocker) were administered 15 min before lasmiditan or sumatriptan injection. To evaluate the underlying signaling pathways, ELISA analysis of inflammatory cytokines (TNF-α and IL-1β) and western blot analysis of anti- and pro-apoptotic markers (Bcl-2 and Bax) were performed on mice isolated brain tissues.

RESULTS

Lasmiditan (0.1 mg/kg, i.p.) and sumatriptan (0.03 mg/kg, i.p.) remarkably decreased seizure susceptibility in stroke animals by reducing inflammatory cytokines and neuronal apoptosis. Concurrent administration of naltrexone (10 mg/kg, i.p.) or glibenclamide (0.3 mg/kg, i.p.) with lasmiditan or sumatriptan resulted in a higher neuroprotection against clonic seizures and efficiently reduced the inflammatory and apoptotic markers.

CONCLUSION

Lasmiditan and sumatriptan significantly increased post-stroke seizure thresholds in mice by suppressing inflammatory cytokines and neuronal apoptosis. Lasmiditan and sumatriptan seem to exert higher effects on seizure threshold with concurrent administration of the opioid receptors or K_ATP channels modulators.

Glibenclamide attenuates brain edema associated with microglia activation after intracerebral hemorrhage

OBJECTIVE

Glibenclamide, Sulfonylurea receptor 1 antagonist, reduces brain edema after cerebral hemorrhage. However, the effects of glibenclamide on microglial activation and inflammatory cell infiltration after cerebral hemorrhage are unclear. The present study investigated the effect of glibenclamide on microglial activation and inflammatory cell infiltration in a rat cerebral hemorrhage model.

METHODS

A collagenase intracerebral injection model was used to cause cerebral hemorrhage in rats. After injury, glibenclamide was continuously administered at 1.0μL/h for 24hours. We evaluated hematoma volume, brain edema, expression of ABCC8, galectin-3 and CD11b, and anti-Iba-1 antibody staining.

RESULTS

Glibenclamide significantly reduced water content. Meanwhile, glibenclamide significantly reduced expression of galectin-3 and CD11b in the cerebral cortex and putamen on the bleeding side. Immunohistochemical staining confirmed that glibenclamide attenuated activation of microglia around the hematoma.

CONCLUSIONS

Glibenclamide reduced microglial activation and infiltration of inflammatory cells, resulting in amelioration of cerebral edema.

Blood-Brain Barrier Alterations and Edema Formation in Different Brain Mass Lesions

Differential diagnosis of brain lesion pathologies is complex, but it is nevertheless crucial for appropriate clinical management. Advanced imaging methods, including diffusion-weighted imaging and apparent diffusion coefficient, can help discriminate between brain mass lesions such as glioblastoma, brain metastasis, brain abscesses as well as brain lymphomas. These pathologies are characterized by blood-brain barrier alterations and have been extensively studied. However, the changes in the blood-brain barrier that are observed around brain pathologies and that contribute to the development of vasogenic brain edema are not well described. Some infiltrative brain pathologies such as glioblastoma are characterized by glioma cell infiltration in the brain tissue around the tumor mass and thus affect the nature of the vasogenic edema. Interestingly, a common feature of primary and secondary brain tumors or tumor-like brain lesions characterized by vasogenic brain edema is the formation of various molecules that lead to alterations of tight junctions and result in blood-brain barrier damage. The resulting vasogenic edema, especially blood-brain barrier disruption, can be visualized using advanced magnetic resonance imaging techniques, such as diffusion-weighted imaging and apparent diffusion coefficient. This review presents a comprehensive overview of blood-brain barrier changes contributing to the development of vasogenic brain edema around glioblastoma, brain metastases, lymphomas, and abscesses.

Process of cerebral edema in the infarct core after reperfusion: A case report

RATIONALE

It is generally believed that cerebral infarction shows hypoattenuation on computed tomography (CT) scans 12 to 24 hours after onset. Cerebral edema affects the occurrence of hypoattenuation, originating from the inner edge of the infarct and extending to the core. When reperfusion occurs in the infarct, the process of cerebral edema changes significantly, affecting the imaging of cerebral infarction on CT scans. This article focused on the mechanism of cerebral edema to provide a new perspective for understanding the impact of reperfusion on cerebral infarction.

PATIENT CONCERNS

We describe the case of a 77-year-old man who presented with an acute onset of right limb weakness with speech difficulties 10 hours before the visit. He had been diagnosed with atrial fibrillation 4 months ago. During the acute phase of infarction, the central area of the hypoattenuated infarct appears as isodensity on CT scans in this case.

DIAGNOSES

The patient was diagnosed with acute cerebral infarction, cardiogenic cerebral embolism, and spontaneous recanalization of left middle cerebral artery occlusion.

INTERVENTIONS

Metoprolol was given to control the ventricular rate. The patient received blood pressure control, symptomatic management, and rehabilitation treatments.

OUTCOMES

Finally, the patient became alert.

LESSONS

Cerebral edema originating directly in the infarct core after reperfusion could lead to a significantly accelerated edema process and imaging evolution, causing more severe cerebral damage. In such a case, the patient should not receive antiplatelet and anticoagulant therapy in order to prevent bleeding conversion.

Glutamate excitotoxicity: Potential therapeutic target for ischemic stroke

Glutamate-mediated excitotoxicity is an important mechanism leading to post ischemic stroke damage. After acute stroke, the sudden reduction in cerebral blood flow is most initially followed by ion transport protein dysfunction and disruption of ion homeostasis, which in turn leads to impaired glutamate release, reuptake, and excessive N-methyl-D-aspartate receptor (NMDAR) activation, promoting neuronal death. Despite extensive evidence from preclinical studies suggesting that excessive NMDAR stimulation during ischemic stroke is a central step in post-stroke damage, NMDAR blockers have failed to translate into clinical stroke treatment. Current treatment options for stroke are very limited, and there is therefore a great need to develop new targets for neuroprotective therapeutic agents in ischemic stroke to extend the therapeutic time window. In this review, we highlight recent findings on glutamate release, reuptake mechanisms, NMDAR and its downstream cellular signaling pathways in post-ischemic stroke damage, and review the pathological changes in each link to help develop viable new therapeutic targets. We then also summarize potential neuroprotective drugs and therapeutic approaches for these new targets in the treatment of ischemic stroke.

Hypoxanthine is a pharmacodynamic marker of ischemic brain edema modified by glibenclamide

Brain edema after a large stroke causes significant morbidity and mortality. Here, we seek to identify pharmacodynamic markers of edema that are modified by intravenous (i.v.) glibenclamide (glyburide; BIIB093) treatment. Using metabolomic profiling of 399 plasma samples from patients enrolled in the phase 2 Glyburide Advantage in Malignant Edema and Stroke (GAMES)-RP trial, 152 analytes are measured using liquid chromatography-tandem mass spectrometry. Associations with midline shift (MLS) and the matrix metalloproteinase-9 (MMP-9) level that are further modified by glibenclamide treatment are compared with placebo. Hypoxanthine is the only measured metabolite that associates with MLS and MMP-9. In sensitivity analyses, greater hypoxanthine levels also associate with increased net water uptake (NWU), as measured on serial head computed tomography (CT) scans. Finally, we find that treatment with i.v. glibenclamide reduces plasma hypoxanthine levels across all post-treatment time points. Hypoxanthine, which has been previously linked to inflammation, is a biomarker of brain edema and a treatment response marker of i.v. glibenclamide treatment.

Neuroprotection in Acute Ischemic Stroke: A Battle Against the Biology of Nature

Stroke is the second most common cause of global death following coronary artery disease. Time is crucial in managing stroke to reduce the rapidly progressing insult of the ischemic penumbra and the serious neurologic deficits that might follow it. Strokes are mainly either hemorrhagic or ischemic, with ischemic being the most common of all types of strokes. Thrombolytic therapy with recombinant tissue plasminogen activator and endovascular thrombectomy are the main types of management of acute ischemic stroke (AIS). In addition, there is a vital need for neuroprotection in the setting of AIS. Neuroprotective agents are important to investigate as they may reduce mortality, lessen disability, and improve quality of life after AIS. In our review, we will discuss the main types of management and the different modalities of neuroprotection, their mechanisms of action, and evidence of their effectiveness after ischemic stroke.

Glibenclamide promoted functional recovery following sciatic nerve injury in male Wistar rats

The impact of peripheral nerve damage on a patient's quality of life is severe. The most frequent peripheral nerve crush damage is a sciatic nerve injury. Previous research has shown that glibenclamide (GB) has neuroprotective properties in a variety of oxidative stress-related disorders, including Alzheimer and Parkinson. The goal of this study was to see how GB affected nerve regeneration and improved function of the sciatic nerve in a rat model following a crush injury. We evaluated motor function, sensory recovery, gene expression, and histomorphometry following damage at different time points. Additionally, we assessed atrophy in the gastrocnemius muscle using histology and mass ratio analyses. Our results suggest that 2, 4, 6, and 8 weeks following glibenclamide therapy, promotes the recovery of motor and sensory function in the injured site. Following glibenclamid injection, the mRNA levels of neurotrophic factors (NGF and BDNF) are raised. According to histomorphometry assessment, glibenclamide injection also increased the number of myelinated fibers while decreasing their thickness. These results showed that glibenclamide therapy by decreasing the proinflammatory and oxidant factors may enhance the nerve regeneration. It is clear that more research is needed to confirm these findings.

A glibenclamide-sensitive TRPM4-mediated component of CA1 excitatory postsynaptic potentials appears in experimental autoimmune encephalomyelitis

The transient receptor potential melastatin 4 (TRPM4) channel contributes to disease severity in the murine experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis and to neuronal cell death in models of excitotoxicity and traumatic brain injury. As TRPM4 is activated by intracellular calcium and conducts monovalent cations, we hypothesized that TRPM4 may contribute to and boost excitatory synaptic transmission in CA1 pyramidal neurons of the hippocampus. Using single-spine calcium imaging and electrophysiology, we found no effect of the TRPM4 antagonists 9-phenanthrol and glibenclamide on synaptic transmission in hippocampal slices from healthy mice. In contrast, glibenclamide but not 9-phenanthrol reduced excitatory synaptic potentials in slices from EAE mice, an effect that was absent in slices from EAE mice lacking TRPM4. We conclude that TRPM4 plays little role in basal hippocampal synaptic transmission, but a glibenclamide-sensitive TRPM4-mediated contribution to excitatory postsynaptic responses is upregulated at the acute phase of EAE.

Higher baseline blood glucose is associated with reduced likelihood for successful recanalization in patients with basilar artery occlusion

Purpose

Evidence regarding the effect of mechanical thrombectomy (MT) of basilar artery occlusion (BAO) stroke is yet sparse. As successful recanalization has been suggested as major determinant of outcome, the early identification of modifiable factors associated with successful recanalization could be of importance to improve functional outcome. Hyperglycemia has been associated with enhanced thrombin generation and unfavorably altered clot features.

Objective

We hypothesized that serum baseline glucose is associated with likelihood of vessel recanalization mediated by collateral quality and clot burden in BAO stroke.

Methods

BAO stroke patients who received multimodal CT on admission were analyzed. The association of vessel recanalization defined using modified Thrombolysis in cerebral infarction scale (mTICI) scores 2b-3, and baseline imaging and clinical parameters were tested in logistic regression analyses. Collateral quality and clot burden were evaluated using the Basilar Artery on CT-Angiography (BATMAN) score.

Results

Out of 117 BAO patients, 91 patients (78%) underwent MT. In 70 patients (77%), successful recanalization could be achieved (mTICI 2b/3). In multivariable logistic regression analysis, only a higher BGL (aOR 0.97, 95% CI 0.96–0.99, p = 0.03) and higher BATMAN score (aOR 1.77, 95% CI 1.11–2.82, p = 0.02) were independently associated with vessel recanalization. Application of alteplase, or time from symptom onset-imaging revealed no independent association with recanalization status.

Conclusion

Higher BGL was significantly associated with reduced likelihood for recanalization success besides BATMAN score as a measure of collateral quality and clot burden. BGL could be tested as a modifiable parameter to increase likelihood for recanalization in BAO stroke, aiming to improve functional outcome.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-021-10948-1.

Capping Protein Regulator and Myosin 1 Linker 3 (CARMIL3) as a Molecular Signature of Ischemic Neurons in the DWI-T2 Mismatch Areas After Stroke

Ischemic stroke with a mismatch between diffusion-weighted imaging (DWI) and fluid-attenuated inversion recovery (FLAIR) or T2-weighted images indicates onset within 4.5 h, but the pathological substrates in the DWI-T2 mismatch and T2(+) areas remain elusive. In this study, proteomics was used to explore (1) the protein expression profiles in the T2(+), mismatch, and contralateral areas, and (2) the protein with the highest expression in the T2(+) area in the brains of male Sprague-Dawley rats within 4.5 h after middle cerebral artery occlusion (MCAO). The expression of the candidate protein was further validated in (1) rat brain subjected to MCAO, (2) rat primary cortical neuronal culture with oxygen-glucose deprivation (OGD), and (3) infarcted human brain tissues. This study showed that apoptosis was observed in the T2(+) and mismatch regions and necroptosis in the T2(+) region of rat brains after MCAO. We identified capping protein regulator and myosin 1 linker 3 (CARMIL3) as the candidate molecule in the T2(+) and mismatch areas, exclusively in neurons, predominantly in the cytoplasm, and most abundant in the mismatch area. The CARMIL3(+) neurons and neurites in the mismatch and T2(+) areas were larger than those in the control area, and associated with (1) increased expression of sulfonylurea receptor 1 (SUR1), indicating edema, (2) accumulation of p62, indicating impaired autophagy, and (3) increase in 8-hydroxy-2′-deoxyguanosine (8-OHdG), indicating oxidative stress. The increased expression of CARMIL3 was validated in a cell model of cortical neurons after OGD and in infarcted human brain tissues. In conclusion, this study shows that the mismatch and T2(+) areas within 4.5 h after ischemia are characterized by upregulated expression of CARMIL3 in neurons, particularly the mismatch area, which is associated with neuronal edema, impaired autophagy, and oxidative stress, indicating that CARMIL3 serves as a molecular signature of brain ischemia.

Serum Sulfonylurea Receptor-1 Levels After Acute Supratentorial Intracerebral Hemorrhage: Implication for Prognosis

OBJECTIVE

Sulfonylurea receptor-1 (SUR1) is implicated in acute brain injury. This study was designed to determine relationship between serum SUR1 levels and severity, early neurologic deterioration (END) plus clinical outcome after intracerebral hemorrhage (ICH).

METHODS

Serum SUR1 levels of 131 ICH patients and 131 healthy controls were quantified in this prospective, observational study. END was defined as an increase of 4 or more points in the National Institutes of Health Stroke Scale (NIHSS) score or death within 24 hours after admission. Patients with a modified Rankin scale (mRS) score of 3-6 at 90 days following onset were considered to experience a poor outcome.

RESULTS

Serum SUR1 levels were substantially higher in patients than in controls. Serum SUR1 levels of patients were highly correlated with NIHSS score, Glasgow Coma Scale score, hematoma volume and ICH score. Compared with patients with END or mRS score of 0-2, other remainders had significantly elevated serum SUR1 levels. Serum SUR1 levels independently predicted END and 90-day poor outcome. Under receiver operating characteristic curve, serum SUR1 levels significantly predicted END and a poor outcome at 90 days after hemorrhagic stroke and its predictive value was similar to those of NIHSS score, Glasgow coma scale score, hematoma volume and ICH score.

CONCLUSION

Serum SUR1 levels are highly correlated with severity, END and poor outcome after hemorrhagic stroke, indicating that serum SUR1 may be useful for risk stratification and prognostic prediction of ICH.

Pharmacological Modulation and (Patho)Physiological Roles of TRPM4 Channel-Part 2: TRPM4 in Health and Disease

Transient receptor potential melastatin 4 (TRPM4) is a unique member of the TRPM protein family and, similarly to TRPM5, is Ca²⁺ sensitive and permeable for monovalent but not divalent cations. It is widely expressed in many organs and is involved in several functions; it regulates membrane potential and Ca²⁺ homeostasis in both excitable and non-excitable cells. This part of the review discusses the currently available knowledge about the physiological and pathophysiological roles of TRPM4 in various tissues. These include the physiological functions of TRPM4 in the cells of the Langerhans islets of the pancreas, in various immune functions, in the regulation of vascular tone, in respiratory and other neuronal activities, in chemosensation, and in renal and cardiac physiology. TRPM4 contributes to pathological conditions such as overactive bladder, endothelial dysfunction, various types of malignant diseases and central nervous system conditions including stroke and injuries as well as in cardiac conditions such as arrhythmias, hypertrophy, and ischemia-reperfusion injuries. TRPM4 claims more and more attention and is likely to be the topic of research in the future.

Contemporary Neuroprotection Strategies during Cardiac Surgery: State of the Art Review

Open-heart surgery is the leading cause of neuronal injury in the perioperative state, with some patients complicating with cerebrovascular accidents and delirium. Neurological fallout places an immense burden on the psychological well-being of the person affected, their family, and the healthcare system. Several randomised control trials (RCTs) have attempted to identify therapeutic and interventional strategies that reduce the morbidity and mortality rate in patients that experience perioperative neurological complications. However, there is still no consensus on the best strategy that yields improved patient outcomes, such that standardised neuroprotection protocols do not exist in a significant number of anaesthesia departments. This review aims to discuss contemporary evidence for preventing and managing risk factors for neuronal injury, mechanisms of injury, and neuroprotection interventions that lead to improved patient outcomes. Furthermore, a summary of existing RCTs and large observational studies are examined to determine which strategies are supported by science and which lack definitive evidence. We have established that the overall evidence for pharmacological neuroprotection is weak. Most neuroprotective strategies are based on animal studies, which cannot be fully extrapolated to the human population, and there is still no consensus on the optimal neuroprotective strategies for patients undergoing cardiac surgery. Large multicenter studies using universal standardised neurological fallout definitions are still required to evaluate the beneficial effects of the existing neuroprotective techniques.

Pretreatment of Sulfonylureas Reducing Perihematomal Edema in Diabetic Patients With Basal Ganglia Hemorrhage: A Retrospective Case-Control Study

Background: The sulfonylurea receptor 1–transient receptor potential melastatin 4 (SUR1–TRPM4) channel is a target key mediator of brain edema. Sulfonylureas (SFUs) are blockers of the SUR1–TRPM4 channel. We made two assessments for the pretreatment of SFUs: (1) whether it associates with lower perihematomal edema (PHE) and (2) whether it associates with improved clinical outcomes in diabetic patients who have acute basal ganglia hemorrhage.

Methods: This retrospective case-control study was conducted in diabetic adults receiving regular SFUs before the onset of intracerebral hemorrhage (ICH). All of the patients received the clinical diagnosis of spontaneous basal ganglia hemorrhage. The diagnosis was confirmed by a CT scan within 7 days after hemorrhage. For each case, we selected two matched controls with basal ganglia hemorrhage based on admission time (≤5 years) and age differences (≤5 years), with the same gender and similar hematoma volume. The primary outcome was PHE volume, and the secondary outcomes were relative PHE (rPHE), functional independence according to modified Rankin Scale score and Barthel Index at discharge, and death rate in the hospital.

Results: A total of 27 patients (nine cases and 18 matched controls), admitted between January 1, 2009 and October 31, 2018, were included in our study. There was no significant association between SFU patients and non-SFU patients on PHE volumes [15.4 (7.4–50.2 ml) vs. 8.0 (3.1–22.1) ml, p = 0.100]. Compared to non-SFU patients, the SFU patients had significantly lower rPHE [0.8 (0.7–1.3) vs. 1.5 (1.2–1.9), p = 0.006]. After we adjusted the confounding factors, we found that sulfonylureas can significantly reduce both PHE volume (regression coefficient: −13.607, 95% CI: −26.185 to −1.029, p = 0.035) and rPHE (regression coefficient: −0.566, 95% CI: −0.971 to −0.161, p = 0.009). However, we found no significant improvement in clinical outcomes at discharge, in the event of pretreatment of SFUs before the onset of ICH, even after we adjusted the confounding factors.

Conclusion: For diabetic patients with acute basal ganglia hemorrhage, pretreatment of sulfonylureas may associate with lower PHE and relative PHE on admission. No significant effect was found on the clinical outcomes when the patients were discharged. Future studies are needed to assess the potential clinical benefits using sulfonylureas for ICH patients.

Sulfonylurea Receptor 1 in Central Nervous System Injury: An Updated Review

Sulfonylurea receptor 1 (SUR1) is a member of the adenosine triphosphate (ATP)-binding cassette (ABC) protein superfamily, encoded by Abcc8, and is recognized as a key mediator of central nervous system (CNS) cellular swelling via the transient receptor potential melastatin 4 (TRPM4) channel. Discovered approximately 20 years ago, this channel is normally absent in the CNS but is transcriptionally upregulated after CNS injury. A comprehensive review on the pathophysiology and role of SUR1 in the CNS was published in 2012. Since then, the breadth and depth of understanding of the involvement of this channel in secondary injury has undergone exponential growth: SUR1-TRPM4 inhibition has been shown to decrease cerebral edema and hemorrhage progression in multiple preclinical models as well as in early clinical studies across a range of CNS diseases including ischemic stroke, traumatic brain injury, cardiac arrest, subarachnoid hemorrhage, spinal cord injury, intracerebral hemorrhage, multiple sclerosis, encephalitis, neuromalignancies, pain, liver failure, status epilepticus, retinopathies and HIV-associated neurocognitive disorder. Given these substantial developments, combined with the timeliness of ongoing clinical trials of SUR1 inhibition, now, another decade later, we review advances pertaining to SUR1-TRPM4 pathobiology in this spectrum of CNS disease-providing an overview of the journey from patch-clamp experiments to phase III trials.

Emerging therapeutic targets for cerebral edema

INTRODUCTION

Cerebral edema is a key contributor to death and disability in several forms of brain injury. Current treatment options are limited, reactive, and associated with significant morbidity. Targeted therapies are emerging based on a growing understanding of the molecular underpinnings of cerebral edema.

AREAS COVERED

We review the pathophysiology and relationships between different cerebral edema subtypes to provide a foundation for emerging therapies. Mechanisms for promising molecular targets are discussed, with an emphasis on those advancing in clinical trials, including ion and water channels (AQP4, SUR1-TRPM4) and other proteins/lipids involved in edema signaling pathways (AVP, COX2, VEGF, and S1P). Research on novel treatment modalities for cerebral edema [including recombinant proteins and gene therapies] is presented and finally, insights on reducing secondary injury and improving clinical outcome are offered.

EXPERT OPINION

Targeted molecular strategies to minimize or prevent cerebral edema are promising. Inhibition of SUR1-TRPM4 (glyburide/glibenclamide) and VEGF (bevacizumab) are currently closest to translation based on advances in clinical trials. However, the latter, tested in glioblastoma multiforme, has not demonstrated survival benefit. Research on recombinant proteins and gene therapies for cerebral edema is in its infancy, but early results are encouraging. These newer modalities may facilitate our understanding of the pathobiology underlying cerebral edema.

The effect of Glibenclamide on somatosensory evoked potentials after cardiac arrest in rats

BACKGROUND

Science continues to search for a neuroprotective drug therapy to improve outcomes after cardiac arrest (CA). The use of glibenclamide (GBC) has shown promise in preclinical studies, but its effects on neuroprognostication tools are not well understood. We aimed to investigate the effect of GBC on somatosensory evoked potential (SSEP) waveform recovery post CA and how this relates to the early prediction of functional outcome, with close attention to arousal and somatosensory recovery, in a rodent model of CA.

METHODS

Sixteen male Wistar rats were subjected to 8-min asphyxia CA and assigned to GBC treatment (n = 8) or control (n = 8) groups. GBC was administered as a loading dose of 10 μg/kg intraperitoneally 10 min after the return of spontaneous circulation, followed by a maintenance dosage of 1.6 μg/kg every 8 h for 24 h. SSEPs were recorded from baseline until 150 min following CA. Coma recovery, arousal, and brainstem function, measured by subsets of the neurological deficit score (NDS), were compared between both groups. SSEP N10 amplitudes were compared between the two groups at 30, 60, 90, and 120 min post CA.

RESULTS

Rats treated with GBC had higher sub-NDS scores post CA, with improved arousal and brainstem function recovery (P = 0.007). Both groups showed a gradual improvement of SSEP N10 amplitude over time, from 30 to 120 min post CA. Rats treated with GBC showed significantly better SSEP recovery at every time point (P < 0.001 for 30, 60, and 90 min; P = 0.003 for 120 min). In the GBC group, the N10 amplitude recovered to baseline by 120 min post CA. Quantified Cresyl violet staining revealed a significantly greater percentage of damage in the control group compared with the GBC treatment group (P = 0.004).

CONCLUSIONS

Glibenclamide improves coma recovery, arousal, and brainstem function after CA with decreased number of ischemic neurons in a rat model. GBC improves SSEP recovery post CA, with N10 amplitude reaching the baseline value by 120 min, suggesting early electrophysiologic recovery with this treatment. This medication warrants further exploration as a potential drug therapy to improve functional outcomes in patients after CA.

Cerebrospinal fluid is a significant fluid source for anoxic cerebral oedema

Cerebral edema develops after anoxic brain injury. In two models of asphyxial and asystolic cardiac arrest without resuscitation, we found that edema develops shortly after anoxia secondary to terminal depolarizations and the abnormal entry of cerebrospinal fluid (CSF). Edema severity correlated with the availability of CSF with the age-dependent increase in CSF volume worsening the severity of edema. Edema was identified primarily in brain regions bordering CSF compartments in mice and humans. The degree of ex vivo tissue swelling was predicted by an osmotic model suggesting that anoxic brain tissue possesses a high intrinsic osmotic potential. This osmotic process was temperature-dependent, proposing an additional mechanism for the beneficial effect of therapeutic hypothermia. These observations show that CSF is a primary source of edema fluid in anoxic brain. This novel insight offers a mechanistic basis for the future development of alternative strategies to prevent cerebral edema formation after cardiac arrest.

Glibenclamide Attenuates Neuroinflammation and Promotes Neurological Recovery After Intracerebral Hemorrhage in Aged Rats

Intracerebral hemorrhage (ICH) is a common disease in the elderly population. Inflammation following ICH plays a detrimental role in secondary brain injury, which is associated with a poor prognosis of patients with ICH, and no efficient pharmacological preventions are available. Here, we investigated the effects of glibenclamide (GLC) on neuroinflammation in an autoblood-induced aged rat (18 months old) model of ICH. Rats were randomized into the sham, vehicle, and GLC groups. First, we investigated the expression level of sulfonylurea receptor 1 (Sur1) surrounding the hematoma after ICH. Then, neurological scores were calculated, and water maze tests, brain water content analysis, western blotting, and immunofluorescence assays were implemented to detect the neuroprotective effect of GLC. The expression of the Sur1-Trpm4 channel was significantly increased in the perihematomal tissue following ICH in aged rats. The GLC administration effectively reduced brain edema and improved neurofunction deficits following ICH. In addition, GLC increased the expression of brain-derived neurotrophic factors and decreased the expression of proinflammatory factors [tumor necrosis factor (TNF)-α,interleukin (IL)-1, and IL-6]. Moreover, GLC markedly reduced Ikappa-B (IκB) kinase (IKK) expression in microglia and nuclear factor (NF)-κB-P65 levels in perihematomal tissue. GLC ameliorated ICH-induced neuroinflammation and improved neurological outcomes in aged rats. In part, GLC may exert these effects by regulating the NF-κB signaling pathway through the Sur1-Trpm4 channel.

Cerebral Edema Formation After Stroke: Emphasis on Blood-Brain Barrier and the Lymphatic Drainage System of the Brain

Brain edema is a severe stroke complication that is associated with prolonged hospitalization and poor outcomes. Swollen tissues in the brain compromise cerebral perfusion and may also result in transtentorial herniation. As a physical and biochemical barrier between the peripheral circulation and the central nervous system (CNS), the blood–brain barrier (BBB) plays a vital role in maintaining the stable microenvironment of the CNS. Under pathological conditions, such as ischemic stroke, the dysfunction of the BBB results in increased paracellular permeability, directly contributing to the extravasation of blood components into the brain and causing cerebral vasogenic edema. Recent studies have led to the discovery of the glymphatic system and meningeal lymphatic vessels, which provide a channel for cerebrospinal fluid (CSF) to enter the brain and drain to nearby lymph nodes and communicate with the peripheral immune system, modulating immune surveillance and brain responses. A deeper understanding of the function of the cerebral lymphatic system calls into question the known mechanisms of cerebral edema after stroke. In this review, we first discuss how BBB disruption after stroke can cause or contribute to cerebral edema from the perspective of molecular and cellular pathophysiology. Finally, we discuss how the cerebral lymphatic system participates in the formation of cerebral edema after stroke and summarize the pathophysiological process of cerebral edema formation after stroke from the two directions of the BBB and cerebral lymphatic system.

Glymphatic System in the Central Nervous System, a Novel Therapeutic Direction Against Brain Edema After Stroke

Stroke is the destruction of brain function and structure, and is caused by either cerebrovascular obstruction or rupture. It is a disease associated with high mortality and disability worldwide. Brain edema after stroke is an important factor affecting neurologic function recovery. The glymphatic system is a recently discovered cerebrospinal fluid (CSF) transport system. Through the perivascular space and aquaporin 4 (AQP4) on astrocytes, it promotes the exchange of CSF and interstitial fluid (ISF), clears brain metabolic waste, and maintains the stability of the internal environment within the brain. Excessive accumulation of fluid in the brain tissue causes cerebral edema, but the glymphatic system plays an important role in the process of both intake and removal of fluid within the brain. The changes in the glymphatic system after stroke may be an important contributor to brain edema. Understanding and targeting the molecular mechanisms and the role of the glymphatic system in the formation and regression of brain edema after stroke could promote the exclusion of fluids in the brain tissue and promote the recovery of neurological function in stroke patients. In this review, we will discuss the physiology of the glymphatic system, as well as the related mechanisms and therapeutic targets involved in the formation of brain edema after stroke, which could provide a new direction for research against brain edema after stroke.

Promise of the NLRP3 Inflammasome Inhibitors in In Vivo Disease Models

Nucleotide-binding oligomerization domain NOD-like receptors (NLRs) are conserved cytosolic pattern recognition receptors (PRRs) that track the intracellular milieu for the existence of infection, disease-causing microbes, as well as metabolic distresses. The NLRP3 inflammasome agglomerates are consequent to sensing a wide spectrum of pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs). Certain members of the NLR family have been documented to lump into multimolecular conglomerates called inflammasomes, which are inherently linked to stimulation of the cysteine protease caspase-1. Following activation, caspase-1 severs the proinflammatory cytokines interleukin (IL)-1β and IL-18 to their biologically active forms, with consequent commencement of caspase-1-associated pyroptosis. This type of cell death by pyroptosis epitomizes a leading pathway of inflammation. Accumulating scientific documentation has recorded overstimulation of NLRP3 (NOD-like receptor protein 3) inflammasome involvement in a wide array of inflammatory conditions. IL-1β is an archetypic inflammatory cytokine implicated in multiple types of inflammatory maladies. Approaches to impede IL-1β's actions are possible, and their therapeutic effects have been clinically demonstrated; nevertheless, such strategies are associated with certain constraints. For instance, treatments that focus on systemically negating IL-1β (i.e., anakinra, rilonacept, and canakinumab) have been reported to result in an escalated peril of infections. Therefore, given the therapeutic promise of an NLRP3 inhibitor, the concerted escalated venture of the scientific sorority in the advancement of small molecules focusing on direct NLRP3 inflammasome inhibition is quite predictable.

Aflibercept, a VEGF (Vascular Endothelial Growth Factor)-Trap, Reduces Vascular Permeability and Stroke-Induced Brain Swelling in Obese Mice

Background and Purpose

Brain edema is an important underlying pathology in acute stroke, especially when comorbidities are present. VEGF (Vascular endothelial growth factor) signaling is implicated in edema. This study investigated whether obesity impacts VEGF signaling and brain edema, as well as whether VEGF inhibition alters stroke outcome in obese subjects.

Methods

High-fat diet-induced obese mice were subjected to a transient middle cerebral artery occlusion. VEGF-A and VEGFR2 (receptor) expression, infarct volume, and swelling were measured 3 days post-middle cerebral artery occlusion. To validate the effect of an anti-VEGF strategy, we used aflibercept, a fusion protein that has a VEGF-binding domain and acts as a decoy receptor, in human umbilical vein endothelial cells stimulated with rVEGF (recombinant VEGF; 50 ng/mL) for permeability and tube formation. In vivo, aflibercept (10 mg/kg) or IgG control was administered in obese mice 3 hours after transient 30 minutes middle cerebral artery occlusion. Blood-brain barrier integrity was assessed by IgG staining and dextran extravasation in the postischemic brain. A separate cohort of nonobese (lean) mice was subjected to 40 minutes middle cerebral artery occlusion to test the effect of aflibercept on malignant infarction.

Results

Compared with lean mice, obese mice had increased mortality, infarct volume, swelling, and blood-brain barrier disruption. These outcomes were also associated with increased VEGF-A and VEGFR2 expression. Aflibercept reduced VEGF-A-stimulated permeability and tube formation in human umbilical vein endothelial cells. Compared with the IgG-treated controls, mice treated with aflibercept had reduced mortality rates (40% versus 17%), hemorrhagic transformation (43% versus 27%), and brain swelling (28% versus 18%), although the infarct size was similar. In nonobese mice with large stroke, aflibercept neither improved nor exacerbated stroke outcomes.

Conclusions

The study demonstrates that aflibercept selectively attenuates stroke-induced brain edema and vascular permeability in obese mice. These findings suggest the repurposing of aflibercept to reduce obesity-enhanced brain edema in acute stroke.

Long-Term Oral Treatment with Non-Hypoglycemic Dose of Glibenclamide Reduces Diabetic Retinopathy Damage in the Goto-KakizakiRat Model

Diabetic retinopathy (DR) remains a major cause of vision loss, due to macular edema, retinal ischemia and death of retinal neurons. We previously demonstrated that acute administration of glibenclamide into the vitreous, or given orally at a non-hypoglycemic dose, protected the structure and the function of the retina in three animal models that each mimic aspects of diabetic retinopathy in humans. In this pilot study, we investigated whether one year of chronic oral glibenclamide, in a non-hypoglycemic regimen (Amglidia^®, 0.4 mg/kg, Ammtek/Nordic Pharma, 5 d/week), could alleviate the retinopathy that develops in the Goto-Kakizaki (GK) rat. In vivo, retinal function was assessed by electroretinography (ERG), retinal thickness by optical coherence tomography (OCT) and retinal perfusion by fluorescein and indocyanin green angiographies. The integrity of the retinal pigment epithelium (RPE) that constitutes the outer retinal barrier was evaluated by quantitative analysis of the RPE morphology on flat-mounted fundus ex vivo. Oral glibenclamide did not significantly reduce the Hb1Ac levels but still improved retinal function, as witnessed by the reduction in scotopic implicit times, limited diabetes-induced neuroretinal thickening and the extension of ischemic areas, and it improved the capillary coverage. These results indicate that low doses of oral glibenclamide could still be beneficial for the prevention of type 2 diabetic retinopathy. Whether the retinas ofpatients treated specifically with glibenclamideare less at risk of developing diabetic complications remains to be demonstrated.

Recent advances in nanomedicines for the treatment of ischemic stroke

Ischemic stroke is a cerebrovascular disease normally caused by interrupted blood supply to the brain. Ischemia would initiate the cascade reaction consisted of multiple biochemical events in the damaged areas of the brain, where the ischemic cascade eventually leads to cell death and brain infarction. Extensive researches focusing on different stages of the cascade reaction have been conducted with the aim of curing ischemic stroke. However, traditional treatment methods based on antithrombotic therapy and neuroprotective therapy are greatly limited for their poor safety and treatment efficacy. Nanomedicine provides new possibilities for treating stroke as they could improve the pharmacokinetic behavior of drugs in vivo, achieve effective drug accumulation at the target site, enhance the therapeutic effect and meanwhile reduce the side effect. In this review, we comprehensively describe the pathophysiology of stroke, traditional treatment strategies and emerging nanomedicines, summarize the barriers and methods for transporting nanomedicine to the lesions, and illustrate the latest progress of nanomedicine in treating ischemic stroke, with a view to providing a new feasible path for the treatment of cerebral ischemia.

Glibenclamide does not improve outcome following severe collagenase-induced intracerebral hemorrhage in rats

Intracerebral hemorrhage (ICH) is a devastating insult with few effective treatments. Edema and raised intracranial pressure contribute to poor outcome after ICH. Glibenclamide blocks the sulfonylurea 1 transient receptor potential melastatin 4 (Sur1-Trpm4) channel implicated in edema formation. While glibenclamide has been found to improve outcome and reduce mortality in animal models of severe ischemic stroke, in ICH the effects are less clear. In our previous study, we found no benefit after a moderate-sized bleed, while others have reported benefit. Here we tested the hypothesis that glibenclamide may only be effective in severe ICH, where edema is an important contributor to outcome. Glibenclamide (10 μg/kg loading dose, 200 ng/h continuous infusion) was administered 2 hours post-ICH induced by collagenase injection into the striatum of adult rats. A survival period of 24 hours was maintained for experiments 1-3, and 72 hours for experiment 4. Glibenclamide did not affect hematoma volume (~81 μL) or other safety endpoints (e.g., glucose levels), suggesting the drug is safe. However, glibenclamide did not lessen striatal edema (~83% brain water content), ionic dyshomeostasis (Na+, K+), or functional impairment (e.g., neurological deficits (median = 10 out of 14), etc.) at 24 hours. It also did not affect edema at 72 h (~86% brain water content), or overall mortality rates (25% and 29.4% overall in vehicle vs. glibenclamide-treated severe strokes). Furthermore, glibenclamide appears to worsen cytotoxic edema in the peri-hematoma region (cell bodies were 46% larger at 24 h, p = 0.0017), but no effect on cell volume or density was noted elsewhere. Overall, these findings refute our hypothesis, as glibenclamide produced no favorable effects following severe ICH.

Cerebrovascular effects of glibenclamide investigated using high-resolution magnetic resonance imaging in healthy volunteers

Glibenclamide inhibits sulfonylurea receptor (SUR), which regulates several ion channels including SUR1-transient receptor potential melastatin 4 (SUR1-TRPM4) channel and ATP-sensitive potassium (K_ATP) channel. Stroke upregulates SURl-TRPM4 channel, which causes a rapid edema formation and brain swelling. Glibenclamide may antagonize the formation of cerebral edema during stroke. Preclinical studies showed that glibenclamide inhibits K_ATP channel-induced vasodilation without altering the basal vascular tone. The in vivo human cerebrovascular effects of glibenclamide have not previously been investigated.In a randomized, double-blind, placebo-controlled, three-way cross-over study, we used advanced 3 T MRI methods to investigate the effects of glibenclamide and K_ATP channel opener levcromakalim on mean global cerebral blood flow (CBF) and intra- and extracranial artery circumferences in 15 healthy volunteers. Glibenclamide administration did not alter the mean global CBF and the basal vascular tone. Following levcromakalim infusion, we observed a 14% increase of the mean global CBF and an 8% increase of middle cerebral artery (MCA) circumference, and glibenclamide did not attenuate levcromakalim-induced vascular changes. Collectively, the findings demonstrate the vital role of K_ATP channels in cerebrovascular hemodynamic and indicate that glibenclamide does not inhibit the protective effects of K_ATP channel activation during hypoxia and ischemia-induced brain injury.

The Role of Astrocytes in the Neurorepair Process

Astrocytes are highly specialized glial cells responsible for trophic and metabolic support of neurons. They are associated to ionic homeostasis, the regulation of cerebral blood flow and metabolism, the modulation of synaptic activity by capturing and recycle of neurotransmitters and maintenance of the blood-brain barrier. During injuries and infections, astrocytes act in cerebral defense through heterogeneous and progressive changes in their gene expression, morphology, proliferative capacity, and function, which is known as reactive astrocytes. Thus, reactive astrocytes release several signaling molecules that modulates and contributes to the defense against injuries and infection in the central nervous system. Therefore, deciphering the complex signaling pathways of reactive astrocytes after brain damage can contribute to the neuroinflammation control and reveal new molecular targets to stimulate neurorepair process. In this review, we present the current knowledge about the role of astrocytes in brain damage and repair, highlighting the cellular and molecular bases involved in synaptogenesis and neurogenesis. In addition, we present new approaches to modulate the astrocytic activity and potentiates the neurorepair process after brain damage.

Effectiveness and safety of glibenclamide for stroke: protocol for a systematic review and meta-analysis

INTRODUCTION

Despite the continuous improvement in modern medical treatment, stroke is still a leading cause of death and disability worldwide. How to effectively improve the survival rate and reduce disability in patients who had a stroke has become the focus of many investigations. Recent findings concerning the benefits of glibenclamide as a neuroprotective drug have initiated a new area for prospective studies on the effects of sulfonylureas. Given the high mortality and disability associated with stroke, it is essential to weigh the benefits of neuroprotective drugs against their safety. Therefore, the objective of the current study is to conduct a systematic review using meta-analysis to assess the benefits and safety of glibenclamide as a neuroprotective drug.

METHODS AND ANALYSIS

This study will analyse randomised clinical trials (RCTs) and observational studies published up to 31 December 2020 and include direct or indirect evidence. Studies will be retrieved by searching PubMed, EMBASE, Web of Science, the Cochrane Library and China National Knowledge Infrastructure (CNKI) and WanFang Databases. The outcomes of this study will be mortality, scores from the Modified Rankin Scale and the occurrence of hypoglycaemic events. The risk of bias will be assessed using the Cochrane risk of bias assessment instrument for RCTs. A random-effect/fixed-effect model will be used to summarise the estimates of the mean difference/risk ratio using a 95% CI.

ETHICS AND DISSEMINATION

This meta-analysis is a secondary research project, which is based on previously published data. Therefore, ethical approval and informed consent were not required for this meta-analysis. The results of this study will be submitted to a peer-reviewed journal for publication.

PROSPERO REGISTRATION NUMBER

CRD42020144674.

Hydrogen sulfide attenuates induction and prevents progress of the 6-hydroxydopamine-induced Parkinsonism in rat through activation of ATP-sensitive potassium channels and suppression of ER stress

PURPOSE

Studies argue in favor of hydrogen sulfide (H₂S) as the next potent therapeutic agent for neurodegenerative diseases. In present study, we investigated the effect of long term treatment with NaHS (as donor of H₂S) on induction and progress of the 6-hydroxydopamine (6-OHDA) -induced Parkinsonism in rat.

METHODS

The 6-OHDA was injected into medial forebrain bundle of right hemisphere by stereotaxic surgery. Behavioral tests and treatments were carried out to eight weeks after the toxin. Immunohistochemistry and western blotting were carried out to evaluate the survival of tyrosine hydroxylase (TH) -positive neurons in substantia nigra (SN) and also expression of glucose-regulated protein 78 (GRP78) and C/EBP homologous protein (CHOP), the markers of endoplasmic reticulum (ER) stress, in striatum and SN.

RESULTS

Eight weeks assessment of the behavioral symptoms showed that NaHS especially at dose of 100 μmol/kg attenuates remarkably induction of the Parkinsonism and prevents its progress. NaHS also increased the survival of TH- positive neurons and suppressed 6-OHDA- induced overexpression of GRP78 and CHOP. Blockade of ATP-sensitive potassium (K-ATP) channels with glibenclamide (Glib) prevented markedly the effect of NaHS on both the induction phase and survival of TH- positive neurons. But Glib did not affect the preventing effect of NaHS on the progress phase and its suppressing effect on the overexpression of ER stress markers.

CONCLUSION

H₂S attenuates induction of the 6-OHDA- induced Parkinsonism and also increases the survival of dopaminergic neurons through activation of K-ATP channels. H₂S also prevents progress of the Parkinsonism probably through suppression of ER stress.

BIIB093 (intravenous glibenclamide) for the prevention of severe cerebral edema

Background:

Vasogenic edema in the setting of acute ischemic stroke can be attributed to the opening of transient receptor potential 4 channels, which are expressed in the setting of injury and regulated by sulfonylurea receptor 1 (SUR1) proteins. Glibenclamide, also known as glyburide, RP-1127, Cirara, and BIIB093, is a second-generation sulfonylurea that binds SUR1 at potassium channels and may significantly reduce cerebral edema following stroke, as evidenced by recent clinical trials. This review provides a comprehensive analysis of clinical considerations of glibenclamide use and current patient outcomes when administered in the setting of acute ischemic stroke to reduce severe edema.

Methods:

National databases (MEDLINE, EMBASE, Cochrane, and Google scholar databases) were searched to identify studies that reported on the clinical outcomes of glibenclamide administered immediately following acute ischemic stroke.

Results:

The pharmacological mechanism of glibenclamide was reviewed in depth as well as the known indications and contraindications to receiving treatment. Eight studies were identified as having meaningful clinical outcome data, finding statistically significant differences in glibenclamide treatment groups ranging from matrix metalloproteinase-9 serum levels, midline shift, modified Rankin Scores, National Institute of Health Stroke Score, and mortality endpoints.

Conclusion:

Studies analyzing the GAMES-Pilot and GAMES-PR trials suggest that glibenclamide has a moderate, however, measurable effect on intermediate biomarkers and clinical endpoints. Meaningful conclusions are limited by the small sample size of patients studied.

Continuous Glibenclamide Prevents Hemorrhagic Transformation in a Rodent Model of Severe Ischemia-Reperfusion

BACKGROUND

Endovascular thrombectomy (EVT) is highly effective but may also lead to hemorrhagic transformation (HT) and edema, which may be more pronounced in severe ischemia. We sought to determine whether glibenclamide can attenuate HT and edema in a severe ischemia-reperfusion model that reflects EVT.

METHODS

Using a transient middle cerebral artery occlusion (tMCAo) rodent model of stroke, we studied two rat cohorts, one without rt-PA and a second cohort treated with rt-PA. Glibenclamide or vehicle control was administered as an intravenous bolus at reperfusion, followed by continuous subcutaneous administration with an osmotic pump.

RESULTS

Compared to vehicle control, glibenclamide improved neurological outcome (median 7, interquartile range [IQR 6-8] vs. control median 6 [IQR 0-6], p = 0.025), reduced stroke volume (323 ± 42 vs. 484 ± 60 mm3, p < 0.01), swelling volume (10 ± 4 vs. 28 ± 7%, p < 0.01) and water content (84 ± 1 vs. 85 ± 1%, p < 0.05). Glibenclamide administration also reduced HT based on ECASS criteria, densitometry (0.94 ± 0.1 vs. 1.15 ± 0.2, p < 0.01), and quantitative hemoglobin concentration (2.7 ± 1.5 vs. 6.2 ± 4.6 uL, p = 0.011). In the second cohort with rt-PA coadministration, concordant effects on HT were observed with glibenclamide.

CONCLUSIONS

Taken together, these studies demonstrated that glibenclamide reduced the amount of edema and HT after severe ischemia. This study suggests that co-administration of glibenclamide may be worth further study in severe stroke patients treated with EVT with or without IV rt-PA.

The antidiabetic drug glibenclamide exerts direct retinal neuroprotection

Sulfonylureas, widely used as hypoglycemic agents in adults with type 2 diabetes, have neuroprotective effects in preclinical models of central nervous system injury, and in children with neuropsychomotor impairments linked to neonatal diabetes secondary to ATP-sensitive potassium channel mutations. In the human and rodent retina, we show that the glibenclamide-activated channel sulfonylurea receptor 1 (SUR1) is expressed in the retina and enriched in the macula; we also show that it colocalizes with the potassium channel Kir6.2, and with the cation channel transporter TRPM4. Glibenclamide (glyburide), administered at doses that did not decrease the glycemia, or injected directly into the eye, protected the structure and the function of the retina in various models of retinal injury that recapitulate the pathogenic neurodegenerative events in the diabetic retina. The downregulation of SUR1 using a siRNA suppressed the neuroprotective effects of glibenclamide on excitotoxic stress-induced cell death. The glibenclamide effects include the transcriptional regulation of antioxidant and neuroprotective genes. Ocular glibenclamide could be repurposed for diabetic retinopathy.

An update on the pharmacological management and prevention of cerebral edema: current therapeutic strategies

Introduction: Cerebral edema is a common complication of multiple neurological diseases and is a strong predictor of outcome, especially in traumatic brain injury and large hemispheric infarction.Areas Covered: Traditional and current treatments of cerebral edema include treatment with osmotherapy or decompressive craniectomy at the time of clinical deterioration. The authors discuss preclinical and clinical models of a variety of neurological disease states that have identified receptors, ion transporters, and channels involved in the development of cerebral edema as well as modulation of these receptors with promising agents.Expert opinion: Further study is needed on the safety and efficacy of the agents discussed. IV glibenclamide has shown promise in preclinical and clinical trials of cerebral edema in large hemispheric infarct and traumatic brain injury. Consideration of underlying pathophysiology and pharmacodynamics is vital, as the synergistic use of agents has the potential to drastically mitigate cerebral edema and secondary brain injury thusly transforming our treatment paradigms.

Quantum binding energy features of the drug olmesartan bound to angiotensin type-1 receptors in the therapeutics of stroke

We investigated the binding energies of 105 residues within a 10 Å pocket radius, predicted the energetic relevance of olmesartan regions, and the influence of individual protein segments on OLM -AT1 binding.

Glibenclamide Treatment in Traumatic Brain Injury: Operation Brain Trauma Therapy

Glibenclamide (GLY) is the sixth drug tested by the Operation Brain Trauma Therapy (OBTT) consortium based on substantial pre-clinical evidence of benefit in traumatic brain injury (TBI). Adult Sprague-Dawley rats underwent fluid percussion injury (FPI; n = 45), controlled cortical impact (CCI; n = 30), or penetrating ballistic-like brain injury (PBBI; n = 36). Efficacy of GLY treatment (10-μg/kg intraperitoneal loading dose at 10 min post-injury, followed by a continuous 7-day subcutaneous infusion [0.2 μg/h]) on motor, cognitive, neuropathological, and biomarker outcomes was assessed across models. GLY improved motor outcome versus vehicle in FPI (cylinder task, p < 0.05) and CCI (beam balance, p < 0.05; beam walk, p < 0.05). In FPI, GLY did not benefit any other outcome, whereas in CCI, it reduced 21-day lesion volume versus vehicle (p < 0.05). On Morris water maze testing in CCI, GLY worsened performance on hidden platform latency testing versus sham (p < 0.05), but not versus TBI vehicle. In PBBI, GLY did not improve any outcome. Blood levels of glial fibrillary acidic protein and ubiquitin carboxyl terminal hydrolase-1 at 24 h did not show significant treatment-induced changes. In summary, GLY showed the greatest benefit in CCI, with positive effects on motor and neuropathological outcomes. GLY is the second-highest-scoring agent overall tested by OBTT and the only drug to reduce lesion volume after CCI. Our findings suggest that leveraging the use of a TBI model-based phenotype to guide treatment (i.e., GLY in contusion) might represent a strategic choice to accelerate drug development in clinical trials and, ultimately, achieve precision medicine in TBI.

Strategies to prevent hemorrhagic transformation after reperfusion therapies for acute ischemic stroke: A literature review

BACKGROUND

Reperfusion therapies by tissue plasminogen activator (tPA) and mechanical thrombectomy (MT) have ushered in a new era in the treatment of acute ischemic stroke (AIS). However, reperfusion therapy-related HT remains an enigma.

AIM

To provide a comprehensive review focused on emerging concepts of stroke and therapeutic strategies, including the use of protective agents to prevent HT after reperfusion therapies for AIS.

METHODS

A literature review was performed using PubMed and the ClinicalTrials.gov database.

RESULTS

Risk of HT increases with delayed initiation of tPA treatment, higher baseline glucose level, age, stroke severity, episode of transient ischemic attack within 7 days of stroke onset, and hypertension. At a molecular level, HT that develops after thrombolysis is thought to be caused by reactive oxygen species, inflammation, remodeling factor-mediated effects, and tPA toxicity. Modulation of these pathophysiological mechanisms could be a therapeutic strategy to prevent HT after tPA treatment. Clinical mechanisms underlying HT after MT are thought to involve smoking, a low Alberta Stroke Program Early CT Score, use of general anesthesia, unfavorable collaterals, and thromboembolic migration. However, the molecular mechanisms are yet to be fully investigated. Clinical trials with MT and protective agents have also been planned and good outcomes are expected.

CONCLUSION

To fully utilize the easily accessible drug-tPA-and the high recanalization rate of MT, it is important to reduce bleeding complications after recanalization. A future study direction could be to investigate the recovery of neurological function by combining reperfusion therapies with cell therapies and/or use of pleiotropic protective agents.

Waixenicin A, a marine-derived TRPM7 inhibitor: a promising CNS drug lead

Ion channels are the third largest class of targets for therapeutic drugs. The pharmacology of ion channels is an important research area for identifying new treatment options for human diseases. The past decade or so has seen increasing interest in an ion channel protein belonging to the transient receptor potential (TRP) family, namely the melastatin subfamily member 7 (TRPM7), as an emerging drug target. TRPM7 is a bifunctional protein with a magnesium and calcium-conducting divalent ion channel fused with an active kinase domain. TRPM7 is ubiquitously expressed in human tissues, including the brain, and regulates various cell biology processes such as magnesium and calcium homeostasis, cell growth and proliferation, and embryonic development. TRPM7 provides a link between cellular metabolic status and intracellular calcium homeostasis in neurons due to TRPM7's unique sensitivity to fluctuating intracellular Mg·ATP levels. Thus, the protein plays a key role in ischemic and hypoxic neuronal cell death and brain injury, and is one of the key nonglutamate mechanisms in cerebral ischemia and stroke. Currently, the most potent and specific TRPM7 inhibitor is waixenicin A, a xenicane diterpenoid from the Hawaiian soft coral Sarcothelia edmondsoni. Using waixenicin A as a pharmacological tool, we demonstrated that TRPM7 is involved in promoting neurite outgrowth in vitro. Most recently, we found that waixenicin A reduced hypoxic-ischemic brain injury and preserved long-term behavioral outcomes in mouse neonates. We here suggest that TRPM7 is an emerging drug target for CNS diseases and disorders, and waixenicin A is a viable drug lead for these disorders.

Risk Factors for Hypoglycemia with the Use of Enteral Glyburide in Neurocritical Care Patients

OBJECTIVE

Intravenous glyburide has demonstrated safety when used for attenuation of cerebral edema, although safety data are lacking for enteral glyburide when used for this indication. We aimed to determine the prevalence of and risk factors for hypoglycemia in neurocritical care patients receiving enteral glyburide.

METHODS

We performed a retrospective case-control chart review (hypoglycemia vs. no hypoglycemia) of adult patients who received enteral glyburide for prevention or treatment of cerebral or spinal cord edema. Hypoglycemia was defined as a blood glucose <55.8 mg/dL. Descriptive statistics were used, with multivariate analysis to measure the association of risk factors and outcomes. Logistic regression was applied to outcomes with an exposure. Potential confounders were evaluated using the t-test or the Wilcoxon rank-sum test for continuous variables, and the χ² test or the Fisher exact test for categorical variables.

RESULTS

Seventy-one patients (60.6% men, median age 60 years) were included. The majority received 2.5 mg of enteral glyburide twice daily. Diagnoses included tumors (35.2%), intracerebral hemorrhage (28.2%), postspinal surgery (12.7%), and ischemic stroke (12.7%). Hypoglycemia occurred in 17 (23.9%) patients. Multivariate analysis identified admission serum creatinine (odds ratio, 27.2; [1.661, 445.3]; P < 0.05) as a risk factor for hypoglycemia, whereas body mass index >30 (odds ratio, 0.085; [0.008, 0.921]; P < 0.05) was protective.

CONCLUSIONS

Hypoglycemic episodes are common following enteral glyburide in neurocritical care patients. Both patients with and without diabetes mellitus are at risk of hypoglycemia. Elevated admission serum creatinine may increase the risk of hypoglycemia when utilizing glyburide for prevention or treatment of cerebral or spinal cord edema.

Targeting receptor complexes: a new dimension in drug discovery

Targeting receptor proteins, such as ligand-gated ion channels and G protein-coupled receptors, has directly enabled the discovery of most drugs developed to modulate receptor signalling. However, as the search for novel and improved drugs continues, an innovative approach - targeting receptor complexes - is emerging. Receptor complexes are composed of core receptor proteins and receptor-associated proteins, which have profound effects on the overall receptor structure, function and localization. Hence, targeting key protein-protein interactions within receptor complexes provides an opportunity to develop more selective drugs with fewer side effects. In this Review, we discuss our current understanding of ligand-gated ion channel and G protein-coupled receptor complexes and discuss strategies for their pharmacological modulation. Although such strategies are still in preclinical development for most receptor complexes, they exemplify how receptor complexes can be drugged, and lay the groundwork for this nascent area of research.

Emerging Pharmacological Treatments for Cerebral Edema: Evidence from Clinical Studies

Cerebral edema, a common and often fatal companion to most forms of acute central nervous system disease, has been recognized since the time of ancient Egypt. Unfortunately, our therapeutic armamentarium remains limited, in part due to historic limitations in our understanding of cerebral edema pathophysiology. Recent advancements have led to a number of clinical trials for novel therapeutics that could fundamentally alter the treatment of cerebral edema. In this review, we discuss these agents, their targets, and the data supporting their use, with a focus on agents that have progressed to clinical trials.

Emerging neuroprotective strategies for the treatment of ischemic stroke: An overview of clinical and preclinical studies

Stroke is the leading cause of disability and thesecond leading cause of death worldwide. With the global population aged 65 and over growing faster than all other age groups, the incidence of stroke is also increasing. In addition, there is a shift in the overall stroke burden towards younger age groups, particularly in low and middle-income countries. Stroke in most cases is caused due to an abrupt blockage of an artery (ischemic stroke), but in some instances stroke may be caused due to bleeding into brain tissue when a blood vessel ruptures (hemorrhagic stroke). Although treatment options for stroke are still limited, with the advancement in recanalization therapy using both pharmacological and mechanical thrombolysis some progress has been made in helping patients recover from ischemic stroke. However, there is still a substantial need for the development of therapeutic agents for neuroprotection in acute ischemic stroke to protect the brain from damage prior to and during recanalization, extend the therapeutic time window for intervention and further improve functional outcome. The current review has assessed the past challenges in developing neuroprotective strategies, evaluated the recent advances in clinical trials, discussed the recent initiative by the National Institute of Neurological Disorders and Stroke in USA for the search of novel neuroprotectants (Stroke Preclinical Assessment Network, SPAN) and identified emerging neuroprotectants being currently evaluated in preclinical studies. The underlying molecular mechanism of each of the neuroprotective strategies have also been summarized, which could assist in the development of future strategies for combinational therapy in stroke treatment.

Electrochemically Probing Dynamics of Ascorbate during Cytotoxic Edema in Living Rat Brain

Cytotoxic edema is the initial and most important step in the sequence that almost inevitably leads to brain damage. Exploring the neurochemical disturbances in this process is of great significance in providing a measurable biological parameter for signaling specific pathological conditions. Here, we present an electrochemical system that pinpoints a critical neurochemical involved in cytotoxic edema. Specially, we report a molecularly tailored brain-implantable ascorbate sensor (CFE_AA2.0) featuring excellent selectivity and spatiotemporal resolution that assists the first observation of release of ascorbate induced by cytotoxic edema in vivo. Importantly, we reveal that this release is associated with an increase in the amount of cytotoxic edema-inducing agent and that blockage of cytotoxic edema abolishes ascorbate release, further supporting that ascorbate efflux is cytotoxic edema-dependent. Our study holds the promise for understanding the molecular basis of cytotoxic edema that can lead to the discovery of biomarkers or potential therapeutic strategies of brain diseases.